Methods and systems for adjusting an external fixation frame

ABSTRACT

A tool for implementing a correction plan in an external fixation frame having a plurality of adjustment elements or screws, for example, generally includes a driver, a motor, a controller, and a processor. The driver is adapted to engage and rotate each of the screws. The motor is coupled the driver and adapted to rotate the driver. The controller is connected to the motor and configured to control operation of the motor. The controller may determine whether the tool is engaged with a strut and which strut is engaged, and may determine how much the strut has rotated, taking into account intentional or unintentional manual rotation of the tool. The tool may also include features to help ensure proper engagement between the drive and the strut. Variations may be provided in which similar functionality is provided with manual rotation of a motorless tool.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/895,117, filed Feb. 13, 2018, which is continuation of U.S. patentapplication Ser. No. 14/523,150, filed on Oct. 24, 2014 and issued asU.S. Pat. No. 9,987,043 on Jun. 5, 2018, the disclosures of which arehereby incorporated by reference herein.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to methods, tools, and systems foradjusting an external fixation frame. More particularly, the presentdisclosure relates to methods, tools, and systems for repositioning thecomponents of an external fixation frame according to a correction plan.

The external fixation market can be divided into two major segments:acute trauma and reconstructive. The trauma segment generally includesmodular fixators having fewer components and structured for rapidapplication to a patient. These frames may be used for temporizingfixation and may only be on the patient for hours or days.

The reconstructive segment includes ring fixators, such as the Ilizarovframe, for example. Such frames are shown in U.S. Pat. Nos. 4,365,624,4,615,338, 4,978,348, 5,702,389, and 5,971,984. Ring fixators may beused with a combination of pins and wires to achieve a variety ofpolyaxial pin/wire attachments that provide stability. They can achievea full six degrees of freedom and can correct primary deformitieswithout creating secondary deformities. Rotational deformities may alsobe treated with ring fixators. However, mastery of the techniquesinvolved with using ring fixators, as well as the products themselves,can be a long and daunting process.

At times, it may be necessary to realign, reposition, and/or securelyhold two bone elements relative to one another. For example, in thepractice of medicine, bone fragments and the like are sometimes aligned,realigned, and/or repositioned to restore boney continuity and skeletalfunction. At times, this may be accomplished by sudden maneuver,followed by skeletal stabilization with cast, plate and screws,intramedullary devices, or external skeletal fixators.

A bone fragment can be moved, in general, from its original position asin a nonunion or malunion or from its intended position as in congenitaldeformities along six separate movements or degrees of freedom, acombination of three orthogonal translational axes (e.g., typical “X,”“Y” and “Z” axes) and three orthogonal rotational axes (e.g., rotationabout such typical “X,” “Y” and “Z” axes).

External fixation devices may be attached to the boney skeleton withthreaded and/or smooth pins and/or threaded and/or smooth and/or beadedwires. Such constructs may be referred to as orthopaedic externalfixators or external skeletal fixators. External fixators may beutilized to treat acute fractures of the skeleton, soft tissue injuries,delayed union of the skeleton when bones are slow to heal, nonunion ofthe skeleton when bones have not healed, malunion whereby broken orfractures bones have healed in a malposition, congenital deformitieswhereby bones develop a malposition, and bone lengthening, widening, ortwisting.

A circumferential external fixator system was disclosed by G. A.Ilizarov during the early 1950s. The Ilizarov system includes at leasttwo rings or “halos” that encircle a patient's body member (e.g., apatient's leg), connecting rods extending between the two rings,transfixation pins that extend through the patient's boney structure,and connectors for connecting the transfixation pins to the rings. Useof the Ilizarov system to deal with angulation, translation, androtation is disclosed in “Basic Ilizarov Techniques,” Techniques inOrthopaedics®, Vol. 5, No. 4, December 1990, pp. 55-59.

Often, orthopaedic external fixators such as Ilizarov fixators must berepositioned after their initial application. Such modification may benecessary to convert from one correctional axis to another or to convertfrom an initial adjustment type of fixator to a weight bearing type offixator, some of the correctional configurations not being stable enoughfor weight bearing.

A “Steward platform” is a fully parallel mechanism used in flight andautomotive simulators, robotic end-effectors, and other applicationsrequiring spatial mechanisms with high structural stiffness and includesa base platform, a top platform, and six variable limbs extendingbetween the base and top platforms. See S. V. Sreenivasan et al.,“Closed-Form Direct Displacement Analysis of a 6-6 Stewart Platform,”Mech. Mach. Theory, Vol. 29, No. 6, pp. 855-864, 1994.

Taylor et al. U.S. Pat. No. 5,702,389, which entire disclosure is herebyincorporated by reference herein, relates to a fixator that can beadjusted incrementally in six axes by changing strut lengths only,without requiring joints to be unclamped, etc. This patent includes afirst ring member or swash plate for attachment relative to a first boneelement; a second ring member or swash plate for attachment relative toa second bone element. Six adjustable length struts having first endsmovably attached to the first member and second ends movably attached tothe second member are provided. The first ends of the first and secondstruts are joined relative to one another so that movement of the firstend of one of the first and second struts will cause a correspondingmovement of the first end of the other strut, with the first ends of thethird and fourth struts joined relative to one another so that movementof the first end of one of the third and fourth struts will cause acorresponding movement of the first end of the other strut. The thirdand fourth struts and fifth and sixth struts are similarly joined.Second ends of the first and sixth struts joined relative to one anotherso that movement of the second end of one of the first and sixth strutswill cause a corresponding movement of the second end of the otherstrut. Second ends of the second and third struts and fourth and fifthstruts are formed in a similar manner. Thus, changing the length of thestruts effects the positions of the bone segments.

As discussed above, most external fixators should be adjusted over aperiod of time to reposition bone segments. The adjustment of theexternal fixation may be implemented according to a “prescription” orcorrection plan. Physicians may adjust the external fixator at precisetimes over a period of time (e.g., on a daily basis for three weeks).Patients, however, may not desire to visit the physician's office everytime an adjustment is needed. For this reason, external fixators may beadjusted by the patients themselves without the assistance of aphysician. The adjustment of the external fixator should nonethelessstrictly comply with the predetermined correction plan. However,patients may not adjust their own external fixator according to thecorrection plan for a variety of reasons. For instance, patients may notunderstand how to use the external fixator correctly. In addition, whenthe patients themselves adjust the external fixators, physicians may noteven know whether patients are in fact adjusting the external fixatorsaccording to the correction plan. For the foregoing reasons, it isdesirable to provide a tool, system, and/or method for helping a patientimplement a correction plan in an external fixator.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the disclosure, a tool for actuating one ormore of a plurality of adjustment elements of an external fixation frameincludes an identification mechanism adapted to identify each of theplurality of adjustment elements. A driving element may be adapted toactuate one or more of the plurality of adjustment elements according toinstructions received or processed by the tool. A motor may be operablycoupled to the driving element. A first encoder may be adapted to trackactuation of each of the adjustment elements caused by the motor. Asecond rotary encoder may be adapted to track rotation of the pluralityof adjustment elements caused by manual rotation of the tool. The toolmay additionally include a processor configured to receive correctionplan data including a schedule of adjustment times and degree ofrotation of each of the plurality of adjustment elements, receiveidentification data from the identification mechanism, and determine adegree of rotation of at least one of the plurality of adjustmentelements based on information supplied by the first rotary encoder andthe second rotary encoder. In addition or alternatively, the processormay be further configured to instruct the motor to deactivate afterdetermining the degree of rotation of the one of the plurality ofadjustment elements has reached a predetermined limit. In addition oralternatively, the housing may include a first housing portion and asecond housing portion rotatably coupled to the first housing portion.In addition or alternatively, the first rotary encoder may be at leastpartially positioned on the first housing portion and the second rotaryencoder may be at least partially positioned the second housing portion.In addition or alternatively, the driving element may include a firstoutput shaft coupled to the motor and a second output shaft operablycoupled to the first output shaft. In addition or alternatively, thesecond output shaft may include a connector portion configured to coupleto a head of at least one of the plurality of adjustment elements and adistal portion of the housing may include a connector portion configuredto couple to a body of at least one of the plurality of adjustmentelements.

According to another aspect of the disclosure, a method of implementinga correction plan in an external fixation frame having a plurality ofadjustment elements may include engaging a driving element of a tool toone of the plurality of adjustment elements in a first engagementposition, wherein, in the first engagement position, an identificationmechanism of the tool does not recognize an identification tag of theadjustment element. A force may be applied to the tool to transition thetool from the first engagement position to the second engagementposition, wherein, in the second engagement position, the identificationmechanism of the tool does recognize the identification tag of theadjustment element. A motor of the tool may be actuated to drive thedriving element and rotate the adjustment element when the tool is inthe second engagement position. In addition, the step of engaging thedriving element of the tool to the one adjustment element in the firstengagement position may include positioning a distal end of a slidingmember to the one adjustment element, the sliding member being at leastpartially positioned within the driving element. In addition oralternatively, the step of transitioning the tool from the firstengagement position to the second engagement position may include movinga housing of the tool distally with respect to the sliding member whilethe distal end of the sliding member remains in contact with the oneadjustment element. In addition or alternatively, the step of engagingthe drive element of the tool to the one adjustment element in the firstengagement position may include positioning a distal end of a guidemember to the one adjustment element, the guide member being at leastpartially positioned within the driving element. In addition oralternatively, the step of transitioning the tool from the firstengagement position to the second engagement position may include movinga housing of the tool distally with respect to the guide member whilethe distal end of the guide member remains in contact with the oneadjustment element. In addition or alternatively, as the housing of thetool is moved distally with respect to the guide member, a slide memberat least partially positioned within the driving element may slidedistally into the guide member. In addition or alternatively, the stepof actuating the motor of the tool to drive the driving element androtate the adjustment element may be continued until a processor of thetool determines the adjustment element has rotated a predeterminedamount and instructs the motor to deactivate.

According to a further aspect of the disclosure, a tool for trackingprogress of a correction plan in an external fixation frame having aplurality of adjustment elements may include a bushing for fixedlycoupling to a rotatable head of one of the adjustment elements, a firstcomponent of a rotary encoder fixedly coupled to the bushing; and asecond component of a rotary encoder positioned adjacent the firstcomponent and fixedly coupled to a body of the one adjustment element,the first and second components being rotatable relative to one another.In addition, the bushing may include a recess for accepting the head ofthe one adjustment element. In addition or alternatively, the tool mayinclude a battery within the tool to power components of the tool. Inaddition or alternatively, the tool may include a display capable ofindicating a degree of rotation of the head of the one adjustmentelement.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure will now be described withreference to the appended drawings. It is appreciated that thesedrawings depict only some embodiments of the invention and are thereforenot to be considered limiting of its scope.

FIG. 1 is an isometric view of an external fixation frame;

FIG. 2 a schematic diagram of a system for adjusting an externalfixation frame in accordance with an embodiment of the presentdisclosure;

FIG. 3 is an exemplary correction plan in a table form;

FIGS. 4-5 depict a flowchart illustrating a process for adjusting anexternal fixation frame according to a correction plan;

FIG. 6A is a perspective view of a tool for implementing a correctionplan coupled to a strut of an external fixation frame;

FIG. 6B is an enlarged view of the strut of the external fixation frameto which the tool is connected in FIG. 6A;

FIG. 7A is a perspective view of the tool of FIG. 6A;

FIGS. 7B-C are top and side views of the tool of FIG. 7A shown inpartial transparency;

FIG. 7D is a sectional view of the tool of FIG. 7A;

FIG. 8A is a sectional view of the distal end of the tool of FIG. 7Aengaged with the strut of FIG. 6B;

FIG. 8B is an isolated sectional view of the distal end of the tool ofFIG. 7A;

FIG. 9A is a sectional view of a distal end of a tool according toanother aspect of the disclosure engaged to the strut of FIG. 6B in aninitial engagement position;

FIG. 9B is a sectional view of the distal end of the tool of FIG. 9Aengaged with the strut of FIG. 6B in a final engagement position;

FIG. 9C is a sectional view of a manual version of the tool of FIG. 9Ain an initial engagement position;

FIG. 10A is an isolated sectional view of a distal end of a toolaccording to a further aspect of the disclosure;

FIG. 10B is sectional view of the distal end of the tool of FIG. 10Aengaged to the strut of FIG. 6B in an initial engagement position;

FIG. 10C is a sectional view of the distal end of the tool of FIG. 10Aengaged with the strut of FIG. 6B in a final engagement position;

FIG. 10D is a sectional view of a manual version of the tool of FIG. 10Ain an initial engagement position;

FIG. 11A is a side view of a correction indicator coupled to the strutof FIG. 6B; and

FIG. 11B is an isolated sectional view of the correction indicator ofFIG. 11A.

DETAILED DESCRIPTION

The present disclosure describes in detail embodiments of methods andsystems for adjusting an external fixation frame with reference to thedrawings in which like reference numerals designate identical orsubstantially similar parts in each view. As used herein, “clinician”refers to a physician, surgeon, nurse or other care provider and mayinclude support personnel. Also, as used herein, when the term “distal”is used with reference to a device, the term refers to a locationrelatively far away from a user of the device, while the term “proximal”refers to a location relative close to the user.

FIG. 1 illustrates one example of an external fixation frame 10 that maybe utilized with any long bone, in particular, the tibia and the femur,which includes a first ring 14 and a second ring 16. Although rings 14and 16 are illustrated with a closed circular shape, other types ofrings, such as open or non-circular rings may be suitable for use withother external fixation frames. In operation, first ring 14 movesrelative to second ring 16 during a deformity correction process. Insome embodiments, both rings 14, 16 are identical. Rings 14 and 16 mayeach include a worm gear 15 formed around an outer circumference. Twogrooves 17 may be formed in the upper and lower surfaces of ring 14around its circumference adjacent the worm gear 15. Ring 14 (or 16) mayinclude a multi-level configuration with the upper and lower surfaceshaving alternate steps including through holes 24. In certainembodiments, rings 14 and 16 are connected by three variable lengthstruts 18. The three struts 18 have first ends 28 mounted to the firstring 14 via a connector 25 coupled to a sliding or shuttle unit 26,which is circumferentially moveable around ring 14. In severalembodiments, the first ends 28 are connected to sliding or shuttle units26 by a connector 25 having a ball or spherical joint. The rings 14 and16 may be connected to a bone (e.g., tibia) by a plurality of bone pinsor wires (not shown). In some embodiments, the pins or wires areconnected to each ring 14, 16 by connection elements, which are locatedin one or more of a plurality of through holes 24 around thecircumference of the rings 14 and 16. Although holes 24 are shown, anystructure which locates the pins or wires with respect to thecircumference of rings 14 and 16 can be utilized. Lower ends 34 ofstruts 18 may be connected to lower ring 16 by standard universal-joints35, which allow free rotation about only two axes rather than the threeaxes of the spherical joint at the first strut end 28.

Ring 14 may be coupled to a first bone element via pins or wires and,similarly, ring 16 may be coupled to a second bone element by similarpins or wires. Shuttle units 26 are slidable about ring 14 in a track.Each shuttle unit 26 may include a worm or screw 40 configured to meshwith worm gear 15 of first ring 14. Each screw 40 can be driven by adriver, such as a manual driver or automated driver described herein inconnection with FIGS. 7A-10D.

Identification tags 41, such as RFID tags, may be disposed on both sidesof each screw 40. Each identification tag 41 may store identificationdata and may be adapted to generate a signal indicative of theidentification data of a particular screw 40. For instance, theidentification data may include a number or letter assigned to aspecific screw 40, and may be a completely unique identifier. As isdiscussed in greater detail below in connection with FIGS. 7A-10B, asignal reader of a tool may be adapted to read the signals generatedfrom each identification tag 41 to identify the screw 40 associated witha particular identification tag 41. In operation, rotation of screw 40causes shuttle unit 26 to slide about ring 14, thus changing theposition of strut 18. A second connector 29 between strut 18 and ring 16may have a standard universal joint 35, which allows the strut to rotatefreely about two axes, which may be oriented perpendicular to eachother. Each universal joint 35 may include a gear portion 42 and screw43. Screw 43 is adapted to engage gear portion 42 and, similar to screw40, may be rotated by a driver.

Identification tags 44, such as RFID tags, may be disposed on both sidesof each screw 43. Each identification tag 44 may be adapted to produceand/or send a signal containing identification data. The identificationdata may include information distinguishing a particular screw 43 fromothers screws of external fixation frame 10. Thus, each identificationtag 44 may be configured to generate a signal indicative of the locationand identity of a particular screw 43 with respect to the entireexternal fixation frame 10. In addition, the signal generated byidentification tag 44 may be indicative of the side of the screw 43where the tag is located. Similar to identification tags 41,identification tags 44 may be read by a signal reader in order toidentify the screw 43. Although the drawings show screws 40 and 43,external fixation frame may alternatively include any drive elementcapable of being driven by a driver. The signal reader andidentification tags 41 and 44 collectively form an identificationmechanism adapted to identify each and every screw 40 and 43 of externalfixation frame 10. During operation, rotation of screw 43 causes gearportion 42 to pivot about a pin 1, thereby causing strut 18 to changeits orientation relative to the rings 14 and 16. Thus, each of the threesliding shuttle units 26 may be independently controlled and the threeconnectors 29 at the second ring 16 may be independently controlled sothat the ring 14, and therefore the bone element attached to ring 14,can be positioned in proper alignment with ring 16 and the bone elementattached to ring 16. Rings 14 and 16 can be repositioned after theirinitial alignment as desired by the surgeon. Each strut 18 may have avariable or fixed length.

FIG. 2 schematically depicts a tool or system 100 for adjusting externalfixation frame 10. It should be understood that, although one particularembodiment of external fixation frame 10 is described in connection withFIG. 1, tool 100 may be used with other types of external fixationframes having screw-type mechanisms that, upon rotation, cause arelative change in position between ring members of an external fixationframe. One suitable external fixation frame is described in detail inU.S. Pat. No. 8,333,766, the entire disclosure of which is herebyincorporated by reference herein. Another suitable external fixationframe is described in U.S. Pat. No. 7,955,334, the entire disclosure ofwhich is hereby incorporated herein by reference. The mathematics of theincremental adjustments is described in these applications.

In general, the tool 100 may include a processor 102, such as amicroprocessor or central processing unit, capable of executinginstructions for adjusting an external fixation frame 10. The processor102 may include any suitable bus interface 104 for establishingcommunication between tool 100 and an external host computer C, such asa personal computer. Suitable bus interfaces 104, include, but are notlimited to Universal Serial Bus (USB), a serial port, a parallel port,IEEE 1394 interface and Ethernet bus. Regardless of its specific type,bus interface 104 allows transfer of data between tool 100 and hostcomputer C. Host computer C may include a processor P for executinginstructions and a memory module MM for storing data. The bus interface104 allows data stored on memory module MM to be transferred to the tool100. The data transfer between tool 100 and host computer C may beperformed directly or indirectly. For example, data may be transferredbetween tool 100 and host computer C through a network, such as theInternet. The tool 100 may include a memory module 106 to store data,including data transferred from host computer C. The processor 102 cantherefore retrieve and process data from memory module 106. If hostcomputer C is connected to tool 100 through bus interface 104, theprocessor 102 can also retrieve and process data stored on the memorymodule MM of host computer 300.

With continued reference to FIG. 2, tool 100 may further include aninput device 108 for inputting information. Input device 108 is adaptedto accept instructions from a user and is connected to processor 102. Insome embodiments, input device 108 may include a keypad having aplurality of alphanumeric keys and/or function keys configured to beactuated by users. Input device 108 may additionally or alternativelyinclude any other suitable device, means or mechanisms for enteringinformation into tool 100, such a computer mouse, touchpad, trackball,touch screen, etc. In one embodiment, input device 108 includes atouchpad having a flat, touch sensitive screen, which tracks themovement of a finger or stylus across it.

The tool 100 may include a display unit 110 capable of displayingimages. The display unit 110 is connected to processor 102 and mayinclude liquid crystal display (LCD) panel. As discussed in detailbelow, display unit 100 may show information pertinent to the use oftool 100.

Any suitable power supply 112 may be coupled to processor 102 forenergizing tool 100. Power supply 112 may include a DC or AC powersource and/or a battery. The battery may be rechargeable.

The tool 100 may additionally include an alarm 116 capable of generatinga visual signal, an audio signal, and/or a tactile signal. The alarm 116is connected to processor 102. As discussed in detail below, processor102 can execute instructions to activate alarm 116. Alarm 116 mayinclude a buzzer or any other device, means, or mechanism adapted forgenerating a sound or a vibration. As used herein, the term “sound”refers to one or more audio signals across the audible frequency range.Processor 102 may be connected to a clock 118 for measuring time. Clock118 allows the processor 102 to, for example, actuate the alarm 116 atspecified times.

The tool 100 may further include a signal reader 120, such asradio-frequency identification (RFID) reader, capable of reading asignal from a radio-frequency transmitter on each drive element on theframe of, as described below. This signal is indicative of theidentification of a specific component, such as a screw, worm gear, orstrut of the external fixation frame 10. For example, the screws may beidentified by one or more numbers and/or letters. As discussed in detailbelow, each worm gear may have one or more identification tags, such asan RFID tag, configured to send a signal to be read by the signal reader120.

The screws of external fixation frame 10 may be rotated by a driver 126of tool 100. Driver 126 is adapted to engage and rotate the screws ofexternal fixation frame 10. In certain embodiments, a motor 124 isconnected to the driver 126. Upon activation, motor 124 can rotatedriver 126. The operation and activation of motor 124 is controlled by amotor controller 122 connected to processor 102. The motor controller122 may be electronically connected to an angular position sensor 125.Angular position sensor 125 may include a synchro, a resolver, a rotaryvariable differential transformer (RVDT), a rotary potentiometer and/orany suitable rotary encoder. Suitable rotary encoders for angularposition sensor 125 include, but are not limited to, a quadratureencoder and an absolute encoder. The angular position sensor 125 may bedisposed on the shaft of motor 124, on the driver 126, or on the screws.Regardless of its location, the angular position sensor 125 candetermine the angular position of the driver 126 and the screw attachedto the driver. During operation, motor controller 122 controls theoperation of driver 126 based on the instructions received fromprocessor 102 and signals received from angular position sensor 125. Thedriver 126 in turns rotates a screw to adjust external fixation frame10.

The movement of external fixation frame 10 can be controlled by acomputer or processor 102 of tool 100. As discussed above, the processor102 of tool 100 can communicate and interact with host computer C. Hostcomputer C can store and execute an adjustment application to execute aprocess for controlling the movement of external fixation frame 10 overa predetermined period of time. The memory module MM of host computer Ccan store the data and/or instructions necessary to run the adjustmentapplication using processor P. The adjustment application may be aweb-based application. Suitable applications are described, for example,in U.S. patent application Ser. No. 13/167,101, titled “Methods andSystems for Adjusting an External Fixation Frame,” filed Jun. 23, 2011and U.S. patent application Ser. No. 13/770,056, titled “Software forUse with Deformity Correction,” filed Feb. 19, 2013. The disclosures ofboth of the above applications are hereby incorporated by referenceherein.

For purposes of brevity, two brief examples of the use of such anapplication are described below. It should be understood that there maybe a number of other ways in which to create a correction plan forimplantation with an external fixation frame, and the descriptions beloware merely two examples. Upon initiating the application, a clinicianmay create a new case and enter patient date, such as name, age, weight,height, or any other information useful to identify and/or treat thepatient. The clinician may then import one or more digitalrepresentations of the bone to be treated in any suitable format.Suitable formats may include, but are not limited to, Digital Imagingand Communications in Medicine (DICOM) data and digital x-rays images.The clinician may then select the anatomy to be corrected (e.g. rightfemur or left tibia). The bone deformity to be corrected may then beentered into the application. This deformity definition refers to theanatomical misalignment that the external fixation frame 10 willcorrect. The deformity definition (also referred as deformity data) mayinclude information about the rotation, translation, angulation, lengthand vertical translation of the selected bone or anatomy.

The clinician may also enter anatomical limiting factors (ALF)coordinates. ALF refers to factors that may limit the movement of theexternal fixation frame 10. For example, the ALF may relate to the rateof distraction, as moving portions of the anatomy at too fast or slow arate during correction may be disadvantageous. Another ALF may be theposition of the patient's nerves. During correction of the injured ormisaligned bone, stretching of the nerves may occur. Stretching of thenerves should not be too rapid in order to avoid nerve injury. AnotherALF can be the patient's skin. If the skin has been compromised, forexample in case of an open fracture that part of the skin should not bestretch too rapidly to allow the skin to heal. Up to this point, the twoexemplary applications are identical. Following this point, theclinician may choose a pre-operative (“pre-op”) or a post-operative(“post-op”) mode. The pre-op mode is an optional planning tool designedto virtually test the movement of the external fixation frame 10 withoutattaching the external fixation frame to a bone. In the post-op mode,the adjustment application runs while the external fixation frame 10 isattached to a bone to correct that bone.

If the clinician selects the pre-op mode of the adjustment application,the application determines all possible strut combinations based on,among other things, the sizes and positions of the rings 14 and 16. Theapplication then allows the clinician to select a strut combination outof all the possible strut combinations. Once the clinician has selecteda strut combination, the adjustment application generates a correctionplan. The host computer C may then display the correction plan, asimulation of the correction, and a report via any suitable outputdevice, such as a monitor or screen. The report may include, forexample, patient data, selected anatomy, correction plan data, inputteddeformity definition, inputted ALF coordinates, etc.

If the clinician selects the post-op mode, the application may determinethe position of one of the two rings (the “reference” ring) after theclinician enters information regarding the struts and the other of thetwo rings (the “moving” ring). The information may include the size andposition of the reference ring, as well as sizes and orientations of thestruts in relation to the reference ring. The adjustment application maydetermine the position of the moving ring based on, among other things,the inputted digital representations of the bone, anatomy, deformitydefinition, ALF coordinates and the strut information. Subsequently, theadjustment application generates a correction plan.

Based on at least the initial position of the components of the externalfixation frame (and thus the initial position of the deformed bone(s)),the final desired position of the components of the external fixationframe (and thus the final desired position of the corrected bone(s)),and the rate of adjustment of the components, the application maygenerate a correction plan similar to that illustrated in FIG. 3. Thecorrection plan or “prescription” may be in the form of a table, asshown in FIG. 3 and may include strut or screw identification data(e.g., screw number or letter), amount of rotation (e.g., degrees orradians), length of the strut (e.g. millimeters), direction of rotation(e.g., clockwise or counterclockwise), and frequency of rotation (e.g.,in hours and minutes.) Although illustrated in daily increments, thecorrection plan may span over any desired time and may include, forexample, multiple individual adjustments per day. It should be notedthat the correction plan illustrated in FIG. 3 is for an externalfixation system with six struts connecting a first ring to a secondring.

The correction plan may be referenced during manual adjustment of theexternal fixation frame by the patient or medical personnel and/oruploaded directly to the tool 100. For examples, the host computer C maybe connected directly to tool 100 via bus interface 104. For example, aUSB cable may interconnect bus interface 104 and host computer C.Alternatively, communication between host computer C and tool 100 may beestablished through a closed network or an open network, such and theInternet. If communication is established through a network, the tool100 may be connected to the network through another computer. In suchcase, the tool 100 is connected to that computer via bus interface 104.That computer is in turn connected to the network and interacts andcommunicates with host computer C.

With reference again to FIG. 2, tool 100 may include a processor 102adapted to execute the correction application stored on memory module106. Memory module 106 may store the correction plan data used by thecorrection application. The correction application may be used inconjunction with tool 100 to implement a correction plan algorithm orprocess.

FIGS. 4 and 5 illustrate a flowchart of the correction algorithm orprocess 200, which starts at block 202. At block 204, correction plandata generated by the adjustment application, as described above, isdownloaded to tool 100. The correction plan data is stored on memorymodule 106 and may include, but is not limited to, screw identificationinformation (e.g., screw number or letter), amount of rotation (e.g.,degrees or radians), direction of rotation (e.g., clockwise orcounterclockwise), and frequency of rotation (e.g., in hours andminutes). The correction application then validates the correction plandata by, for example, verifying that the data is not corrupted. Theclinician is also given the opportunity to validate the correction planat decision block 208. Accordingly, the correction plan allows theclinician to input whether the correction plan is valid via input device108 of tool 100. If the correction application or the cliniciandetermines that the correction plan is not valid, the correctionapplication displays an error notification or message, such as“Correction Plan Invalid,” at block 210, and then allows the clinicianor the patient to input a valid correction plan at block 204. The errornotification may be displayed via display unit 110 of tool 100. If thecorrection plan is valid, the application plan reads the correction plandata stored on memory module 106 to retrieve the start date of thecorrection plan at block 212.

Based on the retrieved start date, the correction application determinesor calculates the precise time (i.e., adjustment time) of the firstcorrection, at block 214. The correction application then actuates alarm116 to alert the patient that is time to execute a scheduled correctionat block 216. Specifically, processor 102 receives a signal from clock118 at the adjustment time. In response to this signal, the processor102 sends a signal to alarm 116 to actuate it. At block 218, the patientor clinician may then activate the signal reader 120 of tool 100 toidentify the strut or screw to be rotated according to the downloadedcorrection plan. As discussed above, the signal reader 120 may be anRFID reader. The signal reader 120 is then moved close to a screw 40 or43 to read signal generated by the identification tags 41 or 44 in eachscrew 40 or 43. Once the signal reader 120 reads the signal from theidentification tags 41 or 44, the processor 102 of tool 100 identifiesthe screw. The correction application then determines whether theidentified screw corresponds to the screw that needs to be rotatedaccording to the downloaded correction plan at decision block 220. Ifthe identified screw does not need to be rotated at that precise moment(i.e., scheduled adjustment time), an error notification is displayedvia display unit 110, at block 222, and the alarm 116 is actuated atblock 224 to indicate the user that the identified screw does not needto be rotated at the moment. The error notification may include an errormessage, such as “Invalid Screw.” The error message may be displayed atthe same time as the alarm is actuated. In response to the errornotification, the user may use signal reader 120 to identify theappropriate screw 40 or 43.

If the signal reader 120 identifies the screw 40 that should be rotatedaccording to the correction plan, the user may then securely engagedriver 126 to the identified screw 40 or 43. Subsequently, the useractivates the motor 124 to rotate the identified screw 40 or 43 at block226. While the identified screw 40 or 43 rotates, the angular positionsensor 125 measures the angular position of the rotating screw at block228. The angular position sensor 125 sends a signal indicative of theangular position of the identified screw 40 or 43 to the motorcontroller 122. Based on this signal, the motor controller 122determines whether the identified screw 40 or 43 has been rotatedaccording to the correction plan at block 230. If the screw has not beencompletely rotated in accordance with the correction plan, then themotor controller 122 instructs the motor 124 to continue rotating thedriver 126 until the identified screw 40 or 43 has been rotated inaccordance with the correction plan. Conversely, if the identified screwhas been completely rotated according to the correction plan, the motorcontroller 122 instructs the motor 126 to stop rotating driver 126. Thecorrection application then records when the identified screw wasrotated (i.e., execution time) and the status of the rotated screw(e.g., angular position of rotated screw) at block 232. This informationmay be stored on memory module 106.

The system preferably includes a safety feature to ensure that theadjustment elements are rotated the correct amount when being adjustedby the tool. In rare circumstances, the driver may disengage from thescrew head during rotation. In such a case, the system would receive asignal response alerting it that the driver has disengaged from thescrew head, allowing the tool to re-engage the adjustment element and toadjust the element the amount it would have been adjusted but for theprevious disengagement.

At block 234, the correction application determines whether any otherscrew needs to be rotated immediately in accordance with the correctionplan. If more screws need to be rotated, the processor 102 retrieves andreads the adjustment data for the next screw at block 236. Then, theuser may identify the correct screw, at block 218, and rotate said screwas described above. On the other hand, if the correction plan does notprovide for immediate rotation of other screws, the correctionapplication determines whether any other corrections are necessary inthe future, at decision block 238. If more corrections are necessary,the processor 102 determines or calculates the time for the nextcorrection at block 240. At block 242, the correction time may bedisplayed through display unit 110. The clock 118 measures time andsends a signal to processor 102 at the next correction time. In responseto this signal, the processor 102 actuates alarm 116 at block 216. Thecorrection plan then executes the necessary steps to rotate theappropriate screws in accordance with the correction plan, as discussedin detail above. If no more corrections are necessary, the display unit110 displays a message or notification indicating that the correction ofbone has finished. The message may be, for example, “CorrectionFinished.” The correction application then terminates process 200 atblock 246.

Although one particular embodiment of a tool 100 is described above inrelation to a particular external fixation frame 10, it should beunderstood that other embodiments may be suitable to provide similar orenhanced functionality. For example, FIG. 6A illustrates a tool 300engaged with a portion of an external fixation frame 400. It should beunderstood that tool 300 may provide similar functionality for anydevice with components that are to be rotated or otherwise actuated withprecision. In this particular embodiment, tool 300 is engaged with astrut 410 connected to a first ring 420 of external fixation frame 400.It should be understood that external fixation frame 400 would generallyinclude one or more additional rings (not shown) that may take anysuitable shape, including the circular shape of first ring 420. Further,external fixation frame 400 would generally include three or more struts410 connecting the two or more rings as appropriate. Various types ofstruts 410 may be suitable for use with external fixation frame 400, andstruts 410 may be connected to the rings in a variety of ways. Forexample, as illustrated in FIG. 6B, strut 410 may include a flange 412configured to be connected to first ring 420 through one or moreapertures. Strut 410 may include a head 414 at one end thereof, whereinrotation of the head 414 causes a change in the length of strut 410, andthus causes a change in the position of first ring 420 in relation tothe other ring(s) to which strut 410 is coupled. One suitable mechanismfor causing the change in length of strut 410 via rotation of head 414is described in greater detail in U.S. Patent Publication No.2012/0041439, the disclosure of which is hereby incorporated byreference herein. With such a mechanism, head 414 may rotate withrespect to strut connector 415, which, along with flange 412, isrotationally fixed with respect to the ring 420 to which the strut 410is coupled. Strut connector 415 may have a square, hexagonal, octagonal,or other suitable shape.

Tool 300 is illustrated in greater detail in FIGS. 7A-D. Tool 300 mayinclude a housing having a handle portion 302 and an actuation portion304. The handle portion 302 may be at a generally opposite end of thehousing than the actuation portion. The handle portion 302 may beconfigured to be gripped by a user, while the actuation portion 304, ora portion thereof, may be adapted to engage one or more struts, such asstrut 410, of an external fixation frame, such as external fixationframe 400. A motor 306 may be included in the housing. The motor 306 maybe operatively coupled to one or more gear mechanisms, such as planetaryreduction gearbox 309. The motor 306, as well as other components oftool 300, may be powered by one or more internal batteries 307 withinthe housing. In the case that there are no internal batteries configuredto provide power to the motor, the motor 306 may operate on powersupplied through an external power source, for example via a wiredconnection. Tool 300 may also connect to a computer or other externaldevice, for example via a wired or wireless connection, so that the tool300 may receive or transmit data relating to operation of the tool, orany other relevant data. The tool 300 may additionally or alternativelybe supplied with any suitable wireless transmitter and/or receiver forthe transmission and reception of such data. As best seen in FIGS. 7B-C,the tool 300 may include various electronic components 310, for exampleincluding a processor and memory components. In addition, tool 300 mayinclude a display 312 for displaying relevant information to a user. Oneor more input components, such as a button (not illustrated), may bepositioned adjacent the display to allow the user to scroll throughdifferent screens on the display or to otherwise input data or commands.One or more speakers may also be included with tool 300, for example toprovide audible alarms or to provide for other sounds.

In use, when tool 300 is connected to a power source and/or has asufficiently charged internal battery, a user may actuate the motor 306,for example by depressing an actuation button 314 on the tool 300. Uponactuation, motor 306 causes rotation of a driving element. For example,the motor 306 may cause rotation of a first output shaft 316, whichrotation may be transmitted to a second output shaft 318 via anysuitable gear assembly, such as bevel gears 317 and 319 of first andsecond output shafts 316, 318, respectively. A distal end of secondoutput shaft 318 may include a connector 320 having a shapecomplementary to the shape of the head 414 of strut 410, such as asquare or hexagonal shape, such that rotation of second output shaft 318is transmitted to head 414 of strut 410 when the two are connected.

Actuation portion 304 of tool 300, coupled to strut 410, is illustratedin greater detail in FIG. 8A. FIG. 8B shows the actuation portion 304 oftool 300 isolated. After coupling connector 320 of second output shaft318 to head 414 of strut 410, the tool 300 may determine whether thetool 300 is coupled to the correct strut 410. For example, strut 410 mayinclude an identification tag, such as an RFID tag 416, within the head414 of the strut 410. The tool 300 may include an identification tagreader, such as an RFID antenna 328, to read data on the identificationtag. The data may be, for example, a unique code. The RFID tag 416 andRFID antenna 328 may be configured such that the antenna 328 onlyrecognizes the tag 416 when the two are in close proximity, for examplebetween about 1 mm and about 2 mm. With this configuration, the tool 300may be configured to restrict operation of the motor 306 if the tool 300is not engaged with a strut 410. Once the tool 300 is properly engagedwith the head 414 of a strut 410, the RFID antenna 326 and RFID tag 416may be in close enough proximity for the antenna 326 to recognize theparticular strut 410. Based on instructions stored in the electroniccircuitry 310 of the tool 300, the motor 306 may be actuated by the userto rotate strut 410 no more than a prescribed amount. For example, if aninstruction schedule calls for a single revolution of strut 410 at aparticular time, the motor 306 may be actuated only once the antenna 328recognizes the particular strut 410 via the RFID tag 416, and actuationof motor 306 may be restricted once again after the full amount ofprescribed rotation of strut 410 is complete.

In the illustrated embodiment, actuation portion 304 includes a proximalhousing 322, an intermediate housing 324, and a distal housing 326. Whentool 300 is connected to strut 410, a distal portion of distal housing326 is coupled to the connector 415 of strut 410. The distal portion ofdistal housing 326 may have a shape complementary to the shape ofconnector 415 of strut 410, preferably with at least one edge so thatwhen tool 300 is coupled to strut 410, distal housing 326 isrotationally fixed in relation to connector 415. On the other hand, whentool 300 is coupled to strut 410, proximal housing 322 and intermediatehousing 324 are both rotatable with respect to connector 415. Actuationportion 304 may also include an internal housing 323 which may be fixedto intermediate housing 324. Upon actuation of the motor 306, rotationis transmitted to second output shaft 318, as described above. Rotationof second output shaft 318 due to the actuation of motor 306 only willcause little or no rotation of intermediate housing 324. The rotation ofsecond output shaft 318 relative to inner housing 323 may be facilitatedby one or more bearings B of any suitable type, such as ball bearings.Relative motion between second output shaft 318 and internal housing 323may be tracked with a rotary encoder. For example, second output shaft318 may include a flange 330 fixed thereto, with an electromagnetic codewheel 332 fixed to the flange 330. A pulse pattern receiver 334, such asan encoder chip on a printed circuit board, may be operatively fixed tothe internal housing 323. With the above described configuration, as themotor 306 is actuated and torque is transmitted to second output shaft318, the second output shaft 318 including code wheel 332 rotatesrelative to internal housing 323, including pulse pattern receiver 334.Thus, as second output shaft 318 causes strut 410 to rotate, therotation is tracked by the rotary encoder to ensure that the strut 410is rotated as prescribed, and once the prescribed rotation limit isreached, the motor 306 may be instructed to stop, even if the user isstill depressing the actuation button 314.

One potential issue with the configuration described above is that auser may intentionally or unintentionally manually rotate the tool 300before, after, or during actuation of motor 306. If such manual rotationof tool 300 occurs, the output shaft 318 will rotate and cause strut 410to rotate, but internal housing 323 will also rotate in sync with theoutput shaft 318. Because such manual rotation causes simultaneousrotation of the output shaft 318 and the internal housing 323, both thecode wheel 332 and pulse pattern receiver 334 will rotatesimultaneously. Further, since the rotary encoder system tracks onlyrelative rotation between the code wheel 332 and pulse pattern receiver334, rotation of the head 414 of strut 410 due to manual rotation of thetool 300 will not be detected, despite the fact that the manual rotationof the tool 300 is resulting in rotation of the head 414 of strut 410.To account for the above scenario, a second rotary encoder may beincluded with actuation portion 304 of tool 300. For example, a secondrotary encoder may include a second code wheel 336 fixed to the distalhousing 326 and a second pulse pattern receiver 338 fixed to theintermediate housing 324 adjacent the second code wheel 336. Rotation ofoutput shaft 318 due to the actuation of motor 306 is not captured bythe second rotary encoder because distal housing 326 is alwaysrotationally fixed with respect to the connector 415 of strut 410, andactuation of motor 306 does not cause rotation of intermediate housing324. However, manual rotation of tool 300 causes rotation of innerhousing 323 which is fixed to intermediate housing 324, thusintermediate housing 324 rotates with respect to distal housing 326 uponmanual rotation of the tool 300.

Thus, the first rotary encoder may track rotation of the head 414 ofstrut 410 due to the actuation of motor 306, while the second rotaryencoder may track rotation of the head 414 of strut 410 due to manualrotation of tool 300. The tracked values of rotation of the first andsecond rotary encoders may be added (or subtracted, depending on thedirectionality of rotation) to precisely determine how far the head 414has rotated after tool 300 is coupled to strut 410. This precise valuemay be compared to the prescribed rotational limit provided for theparticular strut 410 for the particular time, so that a user does notover rotate strut 410. Once the rotation limit is met, as noted above,the motor 306 is instructed to restrict any further rotation. An alarm,such as an audible alarm, may be activated as well to alert the use thatthe rotational limit has been met. This alarm may be useful, forexample, because even with a disengaged motor 306, manual rotation ofthe tool 300 to cause rotation of the head 414 of strut 410 is possible.The alarm may alert the user to disengage the tool 300 from the strut410, to eliminate the possibility of further unintentional manualrotation of the strut 410. However, if any manual rotation occurs afterdisengagement of the motor 306, that manual rotation may be tracked viathe second rotary encoder and taken into account, for example by beingadded to or subtracted from the next scheduled rotation.

It should be understood that tool 300 may be provided in anotherembodiment without the motor 306. In such an embodiment, all rotation ismanual and may be tracked via the second rotary encoder, with the alarmindicating whether or not rotational limit has been met. In thisembodiment, the first rotary encoder may be unnecessary, and the shapeof the tool may take other more convenient forms for manual rotation,such as a non-angled body with a handle for facilitating a user gripingand rotating the tool manually. Similar to the embodiment describeddirectly above, the manual version of tool 300 may also include adisplay, such as an LCD display, and alarm features, including speakers.

Another embodiment of a tool 500 is illustrated in FIGS. 9A-B. Tool 500is similar to tool 300 in a number of ways, but includes differentfeatures that may help further ensure that tool 500 cannot be actuatedbefore engaging strut 410, and further to help ensure that tool 500remains engaged to strut 410 during operation. Tool 500 may include ahousing similar to tool 300, with a motor, display, and electroniccomponents described above in connection to tool 300. Only an actuationportion 504 of tool 500 is illustrated in FIGS. 9A-B, in initial andfinal stages of engagement, respectively.

In the illustrated embodiment, actuation portion 504 may include aproximal housing 522 and a distal housing 526. Tool 500 may include amotor attached to a first output shaft with a first gear, and a secondoutput shaft 518 connected to a second gear 519, the second gear 519configured to interact with the first gear (not shown) in a similarfashion as described in connection with tool 300. Second output shaft518 may include a hollow portion with a sliding member 580 positionedtherein, the sliding member 580 having a relatively large diameterdistal portion and a relatively small diameter proximal portion. Aspring member 590 may be positioned around the proximal portion ofsliding member 580, with one end of the spring member 590 abutting thedistal portion of the sliding member 580 and the other end of the springmember 590 abutting the second gear 519. The second gear 519 may includea recess therein, for example having a square or hexagon shape, intowhich a portion of the proximal portion of sliding member 580 may enter.

Tool 500 may include an internal housing 523 which may rotate withrespect to proximal case housing 522. Distal housing 526 may have berotationally fixed with respect to connector 415 of strut 410 in asimilar fashion described in connection with tool 300. A flange 530 maybe coupled to second output shaft 518. A first rotary encoder may bepositioned with respect to flange 530 and internal housing 523 to trackrotation of second output shaft 518 with respect to internal housing523, similar to that described above. For example, the first rotaryencoder may include a first code wheel 532 coupled to the flange 530 anda first pulse pattern receiver 534 coupled to the internal housing 523.The first rotary encoder may work in an identical manner to the firstrotary encoder described in connection with tool 300.

Also similar to tool 300, tool 500 may include an identification tagreader, such as a RFID antenna 528, coupled to distal housing 526. Uponinitial engagement of tool 500 with strut 410, as illustrated in FIG.9A, RFID antenna 528 and RFID tag 416 are not aligned. Rather, uponinitial engagement of tool 500 with strut 410, a distal end of slidingmember 580 contacts head 414 of strut 410 to resist such alignmentbetween the RFID antenna 528 and RFID tag 416. Similarly, a connectorportion 520 of second output shaft 518 is less than fully engaged withhead 414 of strut 410, and the distal end of housing 526 is less thanfully engaged with the connector 415 of strut 410. In this initialengagement position, the motor of the tool 500 is restricted from beingactuated as the RFID antenna 528 is not in a position to recognize RFIDtag 416 of strut 410. In order to align the RFID antenna 528 and RFIDtag 416, the user may push tool 500 downward into the final engagementposition shown in FIG. 9B. As shown in FIG. 9B, the force provided bythe user causes spring member 590 to compress as a proximal portion ofslide member 580 slides into the recess in second gear 519. In thisfinal engagement position, the distal end of distal housing 526 is fullyengaged with connector 415 of strut 410. Similarly, the connectorportion 520 of second output shaft 518 is fully engaged with head 414 ofstrut 410. Upon recognition of RFID tag 416 by RFID antenna 528, asignal may be sent to the electronic circuitry to allow the motor to beactivated. With this configuration, the likelihood of accidentallyactuating the motor of tool 500 prior to full engagement of the tool 500with the strut 410 is minimized, for example, because the user may needto intentionally and forcefully press the tool 500 onto the strut 410before actuation of the motor is possible.

Distal housing 526 may be fixed to proximal housing 522, for example by,welding, gluing or other suitable means. In addition, internal housing523 may be fixed to distal housing 526 with similar means. In thisconfiguration, since distal housing 526 is rotationally fixed toconnector 415 of strut 410 when in the fully engaged position, manualrotation of the head 414 of strut 410, whether intentional orunintentional, is prevented. As such, no secondary rotary encoder isneeded to track such movements, since they are restricted by thephysical configuration of tool 500.

It should be noted that various modifications may be made to tool 500,including reconfiguring the tool as a manual tool. For example, in FIG.9C, tool 500′, a manual version of tool 500, is shown. Most componentsof tool 500′ are identical to those of tool 500, with a few exceptionsto provide for manual operation. For example, the motor of tool 500 maybe removed in manual tool 500′. Rather than a motor driving a firstshaft that interacts with a second gear 519 that interacts with a secondoutput shaft 518, manual tool 500′ includes a handle 516′ that extendsout of the housing and which may be grasped by the user. The handle 516′extends through tool 500′ and a distal end of handle 516′ includes arecess similar or identical to the recess in second gear 519 of tool500. With this configuration, the user may grasp the outer housing 522′of manual tool 500′ with one hand, and place it proximate strut 410. Inthe disengaged position shown in FIG. 9C, rotation of handle 516′ willnot drive the second output shaft 518′ because the proximal end of thesliding member 580′ is not within the recess of the distal end of handle516′. Similar to the automatic tool 500, the user may push manual tool500′ down onto strut 410 to engage the manual tool 500′ with the strut410. Once engaged, the user may rotate handle 516′ with the other handto rotate the head 414 of strut 410. Although the general principles ofaction are very similar between automatic tool 500 and manual tool 500′,manual tool 500′ may provide significant cost savings over the use ofautomatic tool 500, without loss of functions such as tracking rotationand helping ensure engagement of the tool to the correct strut 410.

Another embodiment of a tool 600 is illustrated in FIGS. 10A-C. Tool 600is similar to tool 500 in a number of ways, but includes differentfeatures that may help further ensure that tool 600 cannot be actuatedbefore engaging strut 410, and further to help ensure that tool 600remains engaged to strut 410 during operation. Tool 600 may include ahousing similar to tools 300 and 500, with a motor, display, andelectronic components described above in connection to tool 300. Only anactuation portion 604 of tool 600 is illustrated in FIGS. 10A-C, withFIGS. 10B-C showing tool 600 in initial and final stages of engagement,respectively.

In the illustrated embodiment, actuation portion 604 may include aproximal case housing 622, shown in FIGS. 10B-C, and a distal housing626. Tool 600 may include a motor attached to a first output shaft 616with a first gear 617, and a second output shaft 618 operativelyconnected to a second gear 619, the second gear 619 configured tointeract with the first gear in a similar fashion as described inconnection with tool 300. Second output shaft 618 may include a hollowportion with a sliding member 680 and a guide member 685 positionedtherein, a distal end of the sliding member 680 being configured toslide into guide member 685. A proximal end of slide member 680 may bepositioned within a recess in second gear 619. The guide member 685,sliding member 680, and internal recess in second gear 619 may all havecorresponding shapes, such square, hexagonal, octagonal, or the like, tofacilitate transmission of torque between the components, as isdescribed in greater detail below. A first spring member 690 may bepositioned around sliding member 680, with one end of the first springmember 690 abutting a distal end of the second gear 619 and the otherend of the spring member 690 abutting an internal flange of the secondoutput shaft 618. A second spring member 692 may be positioned withinthe recess of second gear 619, with a first end of the second springmember 692 abutting a proximal end of the sliding member 680 and theother end of the second spring member 692 abutting a cap 694 fixed tothe second gear 619.

Tool 600 may include an internal housing 623 rotationally fixed toproximal housing 622 and distal housing 626. A flange 630 may be coupledto second output shaft 618. A first rotary encoder may be positionedwith respect to flange 630 and internal housing 623 to track rotation ofsecond output shaft 618 with respect to internal housing 623, similar tothat described above. For example, the first rotary encoder may includea first code wheel 632 coupled to the flange 630 and a first pulsepattern receiver 634 coupled to the internal housing 623. The firstrotary encoder may work in an identical manner to the first rotaryencoder described in connection with tool 300.

Also similar to tool 300, tool 600 may include an identification tagreader, such as a RFID antenna 628, coupled to distal housing 626. Uponinitial engagement of tool 600 with strut 410, as illustrated in FIG.10B, RFID antenna 628 and RFID tag 416 are not aligned. Rather, uponinitial engagement of tool 600 with strut 410, a distal end of guidemember 685 contacts head 414 of strut 410 to resist such alignmentbetween the RFID antenna 628 and RFID tag 416. Similarly, a connectorportion 620 of second output shaft 618 is not fully engaged with head414 of strut 410, and the distal end of distal housing 626 is less thanfully engaged with the connector 415 of strut 410. In this initialengagement position, the motor of the tool 600 is restricted from beingactuated as the RFID antenna 628 is not in a position to recognize RFIDtag 416 of strut 410. It should be understood that the connector portion620 of second output shaft 618 may include a shape complementary to thehead 414 of strut 410 that permits transmission of torque—for example asquare, hexagonal, or octagonal shape. Similarly, as in tool 300 and400, the distal end of distal housing 626 may include a similarcomplementary shape to the connector 415 of strut 410 to preventrotation of the distal housing 626 with respect to the connector 415.Preferably, as with the embodiments described above, strut 410 includesa fixed connection to ring 420 of external fixator 400, so thatconnector 415 is unable to rotate with respect to the head 414 of strut410.

In order to align the RFID antenna 628 and RFID tag 416, the user maypush tool 600 downward into the final engagement position shown in FIG.10C. The force provided by the user causes second spring member 692 tocompress first as a proximal portion of slide member 680 slides into therecess in second gear 619. As the user continues to apply force aftersecond spring member 692 is compressed, first spring member 690compresses and the distal end of slide member 680 slides distally intoguide member 685. As the first and second spring members 690, 692 arecompressing, the distal ends of second output shaft 618 and distalhousing 626 slide distally over an end of the strut 410 to the finalengagement position. In this final engagement position, the distal endof distal housing 626 is fully engaged with connector 415 of strut 410.Similarly, the connector portion 620 of second output shaft 618 is fullyengaged with head 414 of strut 410. Upon recognition of RFID tag 416 byRFID antenna 628, a signal may be sent to the electronic circuitry toallow the motor to be activated. If the motor starts to cause rotationof the slide member 680 before the edges of the distal end of slidemember 680 are perfectly aligned with corresponding inner edges of guidemember 685 (e.g. hex to hex or octagon to octagon alignment), forceprovided by second spring 692 may help drive slide member 680 intoproper engagement with guide member 685. With this configuration,similar to tool 500, the likelihood of accidentally actuating the motorof tool 600 prior to full engagement of the tool 600 with the strut 410is minimized, for example, because the user may need to intentionallyand forcefully press the tool 600 onto the strut 410 before actuation ofthe motor is possible. Similarly, manual rotation is effectivelyimpossible in this embodiment because the distal end of distal housing626 is rotationally fixed to connector 415 of strut 410, and the fixedconnection between connector 415 and ring 420 prevents rotation ofconnector 415. That, in combination with the rotationally fixedconnection between distal housing 626, internal housing 623, andproximal housing 622, prevents intentional or unintentional manualrotation of the head 414 of strut 410.

As with tool 500, tool 600 may be reconfigured to work as a manual tool.For example, in FIG. 10D, tool 600′, a manual version of tool 600, isshown. Most components of tool 600′ are identical to those of tool 600,with a few exceptions to provide for manual operation. For example, themotor of tool 600 may be removed in manual tool 600′. Rather than amotor driving a first shaft that interacts with a second gear 619 thatinteracts with a second output shaft 618, manual tool 600′ includes ahandle 616′ that extends out of the housing and which may be grasped bythe user. The handle 616′ extends through tool 600′ and a distal end ofhandle 616′ includes a recess similar or identical to the recess insecond gear 619 of tool 600. With this configuration, the user may graspthe outer housing 622′ of manual tool 600′ with one hand, and place itproximate strut 410. In the disengaged position shown in FIG. 10D,rotation of handle 616′ will not drive the second output shaft 618′because the distal end of the sliding member 680′ is not engaged withguide member 685′. Similar to the automatic tool 600, the user may pushmanual tool 600′ down onto strut 410 to engage the manual tool 600′ withthe strut 410. Once engaged, the user may rotate handle 616′ with theother hand to rotate the head 414 of strut 410. Although the generalprinciples of action are very similar between automatic tool 600 andmanual tool 600′, manual tool 600′ may provide significant cost savingsover the use of automatic tool 600, without loss of functions such astracking rotation and helping ensure engagement of the tool to thecorrect strut 410.

For all of the embodiments described above, it should be understood thatother mechanisms of identifying engagement of the tool with a particularstrut may be used other than RFID including, for example, optical RFID,bar codes, and the like. In addition, mechanical means may be used toidentify engagement of the tool with a particular strut. For example, inan external fixation system with three struts (or more or fewer struts)to be adjusted, each strut may include a head with a differentengagement shape including, for example, square, pentagon, and hexagon.The tool may include a group of second output shafts with end connectors(or a single second output shaft with different connectors) havingcorresponding shapes. The user may attach the square connector to thetool, which the tool may recognize. Since the square connector only fitsover the strut with the square head, the motor may be instructed to onlyallow the particular rotation of the square-headed strut according tothe inputted correction schedule. Once adjustment of the square-headedstrut is complete, the user may switch out the connector of the tool forthe hexagon connector and adjust the hexagon-headed strut. The processmay be continued with the remaining struts until each adjustment for aparticular time period of the schedule is completed. When the time comesfor the next adjustment the process may be repeated. Although discussedin terms of rotating struts of external fixators, it should beunderstood that the concepts provided herein apply to rotation of anyrotatable structure where precision is desired.

Similarly, although particular rotary encoders are disclosed above,other means may be used to track movement of the struts 410 of theexternal fixation frame 400. For example, accelerometers or gyrometersmay provide suitable functionality to track the progress of theadjustment of external fixation frame 400 during adjustment periods ofthe correction schedule.

Other systems may be used in addition or alternatively to the toolsdescribed above to facilitate accurate adjustment of struts 410 of anexternal fixation frame 400 by a user. For example, referring to FIGS.11A-B, strut 410 is illustrated with a correction indicator 700 mountedon the strut 410. The correction indicator 700 may include a guidebushing 710, a display 720, a battery 725, a code wheel 732, and a pulsepattern receiver and electronic board 734. The guide bushing 710 andcode wheel 732 may be fixed to one another and fixed to the head 414 ofstrut 410. The guide bushing 710 may include a recess through which head414 of strut 410 extends. Because of the fixed relationship between theguide bushing 710, code wheel 732, and head 414, as a user rotates head414 to change the length of strut 410, guide bushing 710 and code wheel732 rotate in sync with head 414. Pulse pattern receiver 734, on theother hand, may be fixed to a non-rotating portion of strut 410, such asconnector 415 (see FIG. 6B). With this configuration, as head 414 isrotated to change the length of strut 410, code wheel 732 rotates asdescribed above but pulse pattern receiver 734 remains relativelystationary. As such, the rotation of head 414 may be precisely tracked.Preferably, pulse pattern receiver 734 is positioned adjacent code wheel732 for accurate tracking of the rotation of head 414. As noted above,correction indicator 700 may include a display 720, such as an LCDdisplay, and a battery 725 to power the components of the correctionindicator 700.

One correction indicator 700 may be coupled to each strut, eitherpre-surgery or post-surgery, although mounting post-surgery may bepreferable. A user may use a standard driver to rotate the head 414 ofeach strut 410 according to the correction schedule, with eachadjustment tracked and displayed by the correction indicator 700. Forexample, if the correction schedule indicates that a strut should berotated three “clicks” per day for ten days, the total number of“clicks” may be displayed on the correction indicator 700 for thatstrut. After each “click,” the correction indicator 700 may display thetotal number of cumulative “clicks” that the strut 410 has rotated. Assuch, the patient may reference the correction schedule, for example apaper copy or a computer file, and compare the correction schedule tothe information on the display 720 of correction indicator 700 to ensurethat the correction is proceeding according to plan. Once a particularstrut 410 has been adjusted up to the final adjustment amount, thedisplay 720 may indicate that the correction for the strut 410 iscompleted to help ensure the user does not over-rotate the strut 410.

Correction indicator 700 may be a lower cost alternative to themotorized tools described above, as well as their non-motorizedcounterparts, since correction indicator 700 may be used with a fullymanual driver to track progress of a correction plan. Correctionindicator 700 may include various additional components, such as atransmitter to transmit information relating to progress of adjustmentto a computer or other device for viewing by a doctor.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

The invention claimed is:
 1. A method for tracking progress of acorrection plan in an external fixation frame having a plurality ofadjustment elements comprising: coupling a correction indicator to afirst of the plurality of adjustment elements so that a bushing of thecorrection indicator is rotationally fixed relative to a rotatable headof the first adjustment element and a body of the correction indicatoris rotationally fixed relative to a non-rotating portion of the firstadjustment element; engaging a driver to the rotatable head of the firstadjustment element; rotating the driver together with the rotatable headand the bushing so that a first tracking element rotationally fixed tothe bushing rotates with respect to a second tracking elementrotationally fixed to the body; and tracking, via the correctionindicator, an amount of rotation of the rotatable head of the firstadjustment element.
 2. The method of claim 1, further comprisingdisplaying the amount of rotation of the rotatable head of the firstadjustment element on a display of the correction indicator.
 3. Themethod of claim 1, wherein the correction indicator includes a batteryfor powering the correction indicator.
 4. The method of claim 1, whereinthe driver is a motorized driver.
 5. The method of claim 1, wherein thedriver is a non-motorized driver.
 6. The method of claim 1, wherein thecorrection indicator is coupled to the first adjustment element prior tocoupling the external fixation frame to the patient.
 7. The method ofclaim 1, wherein the correction indicator is coupled to the firstadjustment element after coupling the external fixation frame to thepatient.
 8. The method of claim 1, further comprising couplingadditional correction indicators to additional ones of the plurality ofadjustment elements so that each adjustment element of the externalfixation frame is coupled to one correction indicator.
 9. The method ofclaim 1, wherein the amount of rotation is displayed as a discretizedincremental count, each count corresponding to a predetermined value ofrotation.
 10. The method of claim 9, further comprising displaying thediscretized incremental count on the correction indicator.